Concentrations Of AgNPs Research Articles

Application of Green Synthesized Silver Nanoparticles for Dye Wastewater Treatment

A facile one-pot synthesis of silver nanoparticles (AgNPs) was achieved using the ethanolic extract of Cavendish banana florets as source of reducing agents for the conversion of Ag+ to Ag. The appearance of surface plasmon resonance peak between 410–435 nm in the UV Vis spectra confirmed the formation of AgNPs. The effects of different reaction conditions on the size and concentration of AgNPs were evaluated. The optimum conditions identified were pH 7 at 80 °C. Transmission electron microscopy (TEM) revealed spherical AgNPs with a mean particle size of 13.55 nm. On the other hand, energy-dispersive X-ray (EDX) analysis confirmed the presence of silver (Ag) as the bulk element (87.25%). Other elements such as carbon (C) and oxygen (O) are attributed to the capping agents of AgNPs which agrees with the results in the Fourier-transform infrared spectroscopy (FTIR) analysis. The optimized AgNPs were used for dye degradation using methyl orange (MO) as the model dye under acidified conditions. The maximum MO dye degradation of 96.07% and 77.32% at pH 1.5 and 2 were achieved after 10 min and 1320 min, respectively. This highlights the potential use of green-synthesized AgNPs for dye wastewater treatment.

Assessing cytotoxicity and endoplasmic reticulum stress in human blood–brain barrier cells due to silver and copper oxide nanoparticles

AbstractIn recent years, it has been generally accepted that metal-based nanoparticles (NPs) may induce stress in the endoplasmic reticulum (ER), a key organelle where protein folding occurs. We examined ER stress in immortalized human cerebral microvascular cells (hCMEC/D3) after exposure to silver-NPs (Ag-NPs)- and copper oxide-NPs (CuO-NPs) induced toxicity at < 10 nm and < 40 nm or < 50 nm diameters, respectively. In cytotoxicity assessments, cells were exposed to different CuO-NPs (5–400 µg/mL) or Ag-NPs (1–10 µg/mL) concentration ranges for 24 h and 72 h, and tetrazole salt reduction assays (EZ4U) were performed. Also, Ag-NP or CuO-NP effects on cell proliferation, apoptosis (caspase 3/7 assays), and ER stress and cell morphology were evaluated. In ER stress assessments, RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor 6 (ATF6), inositol-requiring enzyme 1 (IRE1a), and others stress factor mRNA levels were determined after 24 h treatment using Real-Time PCR. Increased stress sensors (IRE1a, PERK, and ATF6) mRNA levels were observed after exposure to Ag-NPs (< 10 and < 40 nm) or CuO-NPs (< 50 nm). We investigated the expression of tight junction (TJ) proteins (barrier junctions) and showed that both types of NP reduced of OCLN gene expression. Morphological changes were observed after Ag-NP or CuO-NP exposure using holotomographic microscopy. Our data suggest that Ag- and CuO-NPs should undergo future in vitro and in vivo toxicology studies, especially for downstream biomedical application and occupational risk assessments.

Green Synthesis of Narrow-Size Silver Nanoparticles Using Ginkgo biloba Leaves: Condition Optimization, Characterization, and Antibacterial and Cytotoxic Activities.

Natural products derived from medicinal plants offer convenience and therapeutic potential and have inspired the development of antimicrobial agents. Thus, it is worth exploring the combination of nanotechnology and natural products. In this study, silver nanoparticles (AgNPs) were synthesized from the leaf extract of Ginkgo biloba (Gb), having abundant flavonoid compounds. The reaction conditions and the colloidal stability were assessed using ultraviolet-visible spectroscopy. X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy (FTIR) were used to characterize the AgNPs. AgNPs exhibited a spherical morphology, uniform dispersion, and diameter ranging from ~8 to 9 nm. The FTIR data indicated that phytoconstituents, such as polyphenols, flavonoids, and terpenoids, could potentially serve as reducing and capping agents. The antibacterial activity of the synthesized AgNPs was assessed using broth dilution and agar well diffusion assays. The results demonstrate antibacterial effects against both Gram-positive and Gram-negative strains at low AgNP concentrations. The cytotoxicity of AgNPs was examined in vitro using the CCK-8 method, which showed that low concentrations of AgNPs are noncytotoxic to normal cells and promote cell growth. In conclusion, an environmentally friendly approach for synthesizing AgNPs from Gb leaves yielded antibacterial AgNPs with minimal toxicity, holding promise for future applications in the field of biomedicine.

Synthesized uniform-different sizes silver nanoparticles using TSC and SBH simultaneously for antibacterial application

Silver nanoparticles (AgNPs) in the form of nanospheres from a few nm to 100 nm in diameter were synthesized in a controlled manner using a combination of two reducing agents: sodium borohydride (SBH) and trisodium citrate (TSC). The influence of the size of AgNPs on antibacterial activity was investigated with different concentrations of AgNPs on two types of bacteria: Pseudomonas aeruginosa (PA) and Staphylococcus aureus resistant (SA) while the positive control was Ampicillin (Amp) 50 μg/ml and the negative control was water. AgNPs were investigated for morphology, size and size distribution using transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The optical properties of the AgNPs were investigated by recording their UV–vis absorption spectra. The antimicrobial activity of AgNPs was determined using the disc diffusion method. The results showed that the antibacterial ability of AgNPs depends on both concentration and particle size. With a particle concentration of 50 μg ml−1, the antibacterial ability is the best. The smaller the particle size, the higher the antibacterial ability. The simultaneous use of two reducing agents TSC and SBH is the novelty of the article to synthesize AgNPs particles that are uniform in shape and size while controlling the particle size. On that basis, their antibacterial performance is increased.

Human health risk assessment and uncertainty analysis of silver nanoparticles in water.

Despite frequent detection in environmental waters, literature which quantifies the health risk of silver nanoparticles (Ag NPs) through oral ingestion is scarce. This study compiled literature data to find the removal of Ag NPs from different treatment schemes (i.e., natural, engineered, or hybrid). Ag NP concentrations were found either in surface water or in groundwater based on where the effluent of treatment schemes was discharged, i.e.,either in surface water or in groundwater. Monte-Carlo simulation was carried out for probabilistic assessment of health risks for children for two hypothetical exposure scenarios: (a) ingesting river water while swimming and (b) drinking groundwater. Bio-accessible fraction, dietary metal adsorption factor, and concentrations of silver ions were incorporated to simulate realistic situations. Different treatment schemes were ranked for their nanoparticles' removal efficiency with respect to (i) exceedance probability from guideline value and (ii) health risk to children. Hybrid treatment combinations, i.e., conventional primary and secondary treatment units followed by nature-based units (constructed wetlands and soil aquifer treatment), were ranked the best. The health risk value was found to be less than 1, with the 99th percentile value less than 10-3 in all cases. The maximum allowable concentration of Ag NPs was found to be as low as 1.43 mg/L for groundwater, suggesting probable potential for risk. Uncertainty analysis revealed that the uncertainty of the influent NPs concentration in raw wastewater contributes > 99% to the variance of the hazard index. The results of this work indicate that the use of natural treatment technologies with existing engineered treatments provides higher nanoparticle removal from wastewater without the requirement of any tertiary treatment unit.

Antifungal potential of commercial silver nanoparticles against rice blast pathogen Magnaporthe oryzae

The rice blast caused by Magnaporthe oryzae is one of the major and recurrent threats to sustainable rice production in Bangladesh. To mitigate this problem, the present study was undertaken with the aim to investigate the inhibitory effects of commercially available silver nanoparticles (Ag-NPs) on the growth and development of Magnaporthe oryzae, and control of rice blast disease. In vitro experiments demonstrated that Ag-NPs significantly suppressed the radial growth of fungal mycelium, with the highest inhibition (83.54%) at a concentration of 250 ppm, while Trooper 75 WP at 400 ppm completely inhibited the fungal mycelial growth. The production of conidia and colony formation were also reduced significantly by Ag-NPs treatment. Furthermore, Ag-NPs exhibited a substantial inhibitory effect on the germination of M. oryzae conidia, with complete inhibition observed at concentrations between 200 and 250 ppm. Comparative analyses revealed that the fungicidal effect of Ag-NPs was superior to silver nitrate (AgNO3), suggesting the augmented activity of the nano properties. The sensitivity of M. oryzae to Ag-NPs was determined by calculating EC50 and EC95 values, which indicated a mean EC50 value of 131.5 ppm and a mean EC95 value of 276 ppm. Additionally, in vivo experiments showed that preventive and curative treatments with Ag-NPs significantly reduced disease incidence and severity in rice plants infected with M. oryzae, with efficacy comparable to that of the fungicide Trooper 75 WP. At higher concentrations of Ag-NPs, preventive treatment was found to be more effective than curative treatment in disease control. These findings highlighted the potential of Ag-NPs as an effective alternative for the management of rice blast. Ann. Bangladesh Agric. (2023) 27 (1): 17-30

A crossover study of antimicrobial capacity and biotoxicity of silver nanoparticles

Silver nanoparticles (AgNPs) have a primordial role in the nanotechnology industry since they have great antimicrobial effects against diverse pathogens. AgNP production, use, and discard have been increasing; still, there is debate about the consequences of exposure to AgNPs for animals and humans. The bioaccumulation and toxicity of AgNPs depend on several factors, including AgNP concentration, physicochemical characteristics, and aggregation. So, complete activity and toxicity profiles for each silver nanoparticle synthesized must be performed. The present work aimed to characterize the behavior of specific AgNPs, then crossover of their antimicrobial capacity against Pseudomonas aeruginosa and Staphylococcus aureus with their potential in vitro cytotoxic effects in murine fibroblasts (3T3) and human keratinocytes (HaCat) cell lines, and in vivo general and organ‐specific toxicity in zebrafish embryos and larvae. A high susceptibility of P. aeruginosa and S. aureus to low concentrations of AgNPs was observed, yet a cytotoxic effect was also detected in 3T3 and HaCat cells. Moreover, these concentrations delayed embryonic development in zebrafish embryos and presented morphological abnormalities, neurotoxicity, and cardiotoxicity in zebrafish larvae. The results highlight the importance of jointly evaluating the antimicrobial activity and the toxicological profile of each nanoparticle manufactured; this study presents a suitable platform for such crossover assessment.

Plasmonic Nanocomposites of ZnO-Ag Produced by Laser Ablation and Their Photocatalytic Destruction of Rhodamine, Tetracycline and Phenol.

Hydrosphere pollution by organic pollutants of different nature (persistent dyes, phenols, herbicides, antibiotics, etc.) is one of the urgent ecological problems facing humankind these days. The task of water purification from such pollutants can be effectively solved with the help of modern photocatalytic technologies. This article is devoted to the study of photocatalytic properties of composite catalysts based on ZnO modified with plasmonic Ag nanoparticles. All materials were obtained by laser synthesis in liquid and differed by their silver content and preparation conditions, such as additional laser irradiation and/or annealing of produced powders. The prepared ZnO-Ag powders were investigated by electron microscopy, X-ray diffraction and UV-Vis spectroscopy. Photocatalytic tests were carried out with well- known test molecules in water (persistent dye rhodamine B, phenol and common antibiotic tetracycline) using LED light sources with wavelengths of 375 and 410 nm. The introduction of small concentrations (up to 1%) of plasmonic Ag nanoparticles is shown to increase the efficiency of the ZnO photocatalyst by expanding its spectral range. Both the preparation conditions and material composition were optimized to obtain composite photocatalysts with the highest efficiency. Finally, the operation mechanisms of the material with different distribution of silver are discussed.

Modification of AgNP-Decorated PET: A Promising Strategy for Preparation of AgNP-Filled Nuclear Pores in Polymer Membranes.

Polymer-based membranes represent an irreplaceable group of materials that can be applied in a wide range of key industrial areas, from packaging to high-end technologies. Increased selectivity to transport properties or the possibility of controlling membrane permeability by external stimuli represents a key issue in current material research. In this work, we present an unconventional approach with the introduction of silver nanoparticles (AgNPs) into membrane pores, by immobilising them onto the surface of polyethyleneterephthalate (PET) foil with subsequent physical modification by means of laser and plasma radiation prior to membrane preparation. Our results showed that the surface characteristics of AgNP-decorated PET (surface morphology, AgNP content, and depth profile) affected the distribution and concentration of AgNPs in subsequent ion-track membranes. We believe that the presented approach affecting the redistribution of AgNPs in the polymer volume may open up new possibilities for the preparation of metal nanoparticle-filled polymeric membranes. The presence of AgNPs on the pore walls can facilitate the grafting of stimuli-responsive molecules onto these active sites and may contribute to the development of intelligent membranes with controllable transport properties.

Tetrazole-stabilized Ag nanoparticles incorporated into TiO2 nanotubes for oxygen electroreduction

Ag NPs stabilized with 5-(2-mercaptoethyl)tetrazole were immobilized on titania nanotubes for the oxygen reduction reaction. The activity of the TiO2/Ag electrocatalysts correlates with the TiO2 doping level and concentration of Ag NPs.

The attract-kill inhibition mechanism in Ag/chitosan hydrogel for long-acting control of Ralstonia solanacearum.

In this study, we developed an innovative eco-friendly antiseptic nanocomposite, specifically a silver nanoparticle (Ag NP)-immobilized chitosan hydrogel (Ag@Cs/Csh gel), synthesized through a cross-linking reaction involving polyvinylpyrrolidone (PVP) and tetraethyl orthosilicate (TEOS). This nanocomposite was designed to combat Ralstonia solanacearum (R. solanacearum) infections, particularly in Solanaceae plants. Chitosan of varying molecular weights (50-190 kDa for Cs and 300-375 kDa for Csh) was used to control the swelling efficacy and regulate the release of Ag NPs. The gels were loaded with either 0.1 or 0.25 mg of Ag NPs and assessed for their antibacterial efficacy against R. solanacearum at various concentrations using the turbidity method. At 5 × 104 CFU mL-1, all gel samples, except for controls, exhibited notable antibacterial activity lasting up to 18.5 days. At higher concentrations of 5 × 106 and 5 × 108 CFU mL-1, the 0.25-Ag@Cs/Csh gel achieved nearly 100% eradication over 18.5 days. Notably, parallel experiments with various concentrations of Ag NPs alone showed limited antibacterial effectiveness against R. solanacearum. Therefore, we propose an "attract and kill" antibacterial mechanism to elucidate the enhanced disinfection capability of the Ag@Cs/Csh gel. Initially, the positively charged chitosan hydrogel attracts negatively charged bacteria, followed by steady Ag+ ion release to eradicate them, providing potent and prolonged antibacterial efficacy.

Synthesis and antibacterial effects of silver nanoparticles (AgNPs) against multi-drug resistant bacteria.

The emergence of the global problem of multi-drug resistant bacteria (MDR) is closely related to the improper use of antibiotics, which gives birth to an urgent need for antimicrobial innovation in the medical and health field. Silver nanoparticles (AgNPs) show significant antibacterial potential because of their unique physical and chemical properties. By accurately regulating the morphology, size and surface properties of AgNPs, the antibacterial properties of AgNPs can be effectively enhanced and become a next generation antibacterial material with great development potential. The detection of the inhibitory effect of AgNPs on MDR provides more possibilities for the research and development of new antimicrobial agents. Promote the formation of AgNPs by redox reaction; determine the minimum inhibitory concentration (MIC) of AgNPs to bacteria by broth microdilution method; evaluate the killing efficacy of AgNPs against multi-drug-resistant bacteria by plate counting; evaluate the inhibitory effect of AgNPs on biofilm construction by crystal violet staining; study the drug resistance of bacteria by gradually increasing the concentration of AgNPs; and detect the toxicity of AgNPs to cells by CCK-8 method. AgNPs has a significant bactericidal effect on a variety of drug-resistant bacteria. After exposure to AgNPs solution for 12 hours, the number of E. coli decreased sharply, and S. aureus was basically eliminated after 16 hours. In particular, AgNPs showed stronger inhibition against Gram-negative bacteria. In addition, AgNPs can effectively hinder the formation of bacterial biofilm, and its inhibitory effect increases with the increase of AgNPs solution concentration. When AgNPs is used for a long time, the development of bacterial resistance to it is slow. From the point of view of safety, AgNPs has no harmful effects on organisms and has biosafety. AgNPs can inhibit MDR, and the bacteriostatic ability of Gram-negative bacteria is higher than that of Gram-positive bacteria. It can also inhibit the formation of bacterial biofilm, avoid drug resistance and reduce cytotoxicity.

In Vitro Effects of Silver Nanoparticles on Pathogenic Bacteria and on Metabolic Activity and Viability of Human Mesenchymal Stem Cells.

The rapid development of nanotechnology has led to the use of silver nanoparticles (Ag-NPs) in various biomedical fields. However, the effect of Ag-NPs on human mesenchymal stem cells (hMSCs) is not fully understood. Moreover, too frequent an exposure to products containing nanosilver in sublethal amounts raises widespread concerns that it will lead to the development of silver-resistant microorganisms. Therefore, this study aimed to evaluate the mechanism of action of Ag-NPs on hMSCs by analyzing the cellular uptake of Ag-NPs by the cells and its effect on their viability and to assess antimicrobial activity of Ag-NPs against emerging bacterial strains, including multidrug-resistant pathogens. For metabolic activity and viability evaluation, hMSCs were incubated with different concentrations of Ag-NPs (14 μg/mL, 7 μg/mL, and 3.5 μg/mL) for 10 min., 1 h and 24 h and subsequently analyzed for their viability by live-dead staining and metabolic activity by the MTS assay. The effect of Ag-NPs on bacterial pathogens was studied by determining their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). In conclusion, it was observed that exposure of hMSCs to Ag-NPs of size <10 nm has no cytotoxic effect on the metabolic activity of the cells at the concentration of 3.5 μg/mL, with minimal cytotoxic effect being observed at the concentration of 14 μg/mL after 24 h of incubation. Our findings also confirmed that Ag-NPs at the concentration of 4 μg/mL are effective broad-spectrum bactericidal agents, regardless of the antibiotic-resistance mechanism present in bacteria.

Fungal-mediated synthesis of silver nanoparticles: a novel strategy for plant disease management.

Various traditional management techniques are employed to control plant diseases caused by bacteria and fungi. However, due to their drawbacks and adverse environmental effects, there is a shift toward employing more eco-friendly methods that are less harmful to the environment and human health. The main aim of the study was to biosynthesize silver Nanoparticles (AgNPs) from Rhizoctonia solani and Cladosporium cladosporioides using a green approach and to test the antimycotic activity of these biosynthesized AgNPs against a variety of pathogenic fungi. The characterization of samples was done by using UV-visible spectroscopy, SEM (scanning electron microscopy), FTIR (fourier transmission infrared spectroscopy), and XRD (X-ray diffractometry). During the study, the presence of strong plasmon absorbance bands at 420 and 450 nm confirmed the AgNPs biosynthesis by the fungi Rhizoctonia solani and Cladosporium cladosporioides. The biosynthesized AgNPs were 80-100 nm in size, asymmetrical in shape and became spherical to sub-spherical when aggregated. Assessment of the antifungal activity of the silver nanoparticles against various plant pathogenic fungi was carried out by agar well diffusion assay. Different concentration of AgNPs, 5 mg/mL 10 mg/mL and 15 mg/mL were tested to know the inhibitory effect of fungal plant pathogens viz. Aspergillus flavus, Penicillium citrinum, Fusarium oxysporum, Fusarium metavorans, and Aspergillus aflatoxiformans. However, 15 mg/mL concentration of the AgNPs showed excellent inhibitory activity against all tested fungal pathogens. Thus, the obtained results clearly suggest that silver nanoparticles may have important applications in controlling various plant diseases caused by fungi.

Zn solubilizing bacteria (ZSB) mitigate toxicity of silver and Titanium dioxide nanoparticles in Mung bean by increasing photosynthetic pigment content.

Zn-deficiency, a global health challenge affects one-third of the world population. Zn-biofertilizer offer an efficient and cost-effective remedy. As Zn-biofertilizer can improve plant growth and grain's Zn-content ensuring improved dietary Zn-supply. This study sought to understand how silver and TiO2 nanoparticles in the rhizosphere affect the activity of Zn-solubilization bacteria (ZSB) and plant growth. Two ZSB strains Bacillus sp. D-7 and Pseudomonas sp. D-117 with excellent Zn-solubilization efficiency of 254 and 260%, respectively were isolated and characterized using polyphasic characterization including 16S rRNA gene sequencing to formulate an effective Zn-biofertilizer. The plant growth promoting activity of this biofertilizer in Mung bean was checked in the presence and absence of various doses of TiO2 and Ag-NPs and was compared with plant grown without biofertilizer. The change in rate of seed germination, vegetative growth (shoot and root length, fresh and dry weight), photosynthetic pigment and Zn-content was checked. Lower doses of nanomaterials (50 and 100 mg kg⁻¹ soil) slightly promoted the plant growth compared to control. While, higher doses (200 and 400 mg kg⁻¹ soil) inhibited the growth. A maximum decrease of shoot length, root length, fresh-weight, and dry-weight of 57.1, 53.9, 53.1, and 10.4% respectively was observed with 400 mg kg⁻¹ of Ag-NPs. However, in the presence of ZSB, the decrease at the same Ag-NP concentration was 41.6, 31.5, 27.4, and 6.6, respectively. These results strongly suggest that Zn-solubilizing bacteria improve resilience to nanoparticles toxicity and helps in Zn fortification in Mung bean even under nanomaterial stress.

Synthesis, antimicrobial and antioxidant bioevaluation of silver nanoparticles using leaf extract of Sarcochlamys pulcherrima

In the present study, aqueous leaf extract of an underutilized vegetable Sarcochlamys pulcherrima was used to establish a straightforward, economical, and environmentally benign method for the synthesis of silver nanoparticles (AgNPs) with potent antioxidant and antibacterial activity. The synthesized AgNPs were characterized by UV-Vis spectroscopy, FT-IR spectroscopy, X-Ray diffraction (XRD)- and transmission electron microscopy (TEM) analysis. In the UV-Vis spectrum, the AgNP samples exhibited characteristic surface plasmon resonance band within 405–432 nm. The average crystallite size of the AgNPs calculated from the XRD data was found to be within the range of 15.6–25.6 nm. TEM analyses showed that most of the synthesised nanoparticles were spherical having dimensions in the range of 6–61 nm. The AgNPs exhibited significant antioxidant activity in the DPPH radical scavenging assay with a maximum of 89.12% inhibitory potential for the sample SP-8 and showed efficient anti-microbial potential against pathogenic bacterium Bacillus subtilis and Pseudomonas aeruginosa. The minimum inhibitory concentration (MIC) value of the sample SP-1 was found to be 0.78 μg/mL against P. aeruginosa which is at per with the MIC value of the standard neomycin (0.78 μg/mL). The minimum bactericidal concentrations (MBC) of the as-synthesized AgNPs for the selected bacterial strains were determined at concentrations of 25.0 μg/mL (B. subtilis) and 1.56 μg/mL (P. aeruginosa). This study concludes that the leaf extracts of the edible plant S. pulcherrima can be successfully utilised for convenient synthesis of AgNPs with antioxidant and antimicrobial potential.

Green synthesis of non-toxic silver nanoparticles using Salvia tebesana Bunge extract: Optimization, cytotoxicity, and antibacterial activities

The remarkable antibacterial activity and potential biomedical applications of silver nanoparticles (AgNPs) synthesized through eco-friendly approaches have garnered significant attention in recent years. This research aimed to introduce a green synthesis method for AgNPs using Salvia tebesana (S. tebesana) Bunge extract and to investigate their properties, antibacterial activities, and cytotoxicity effects. The fabricated AgNPs were analyzed with various analyses, including UV–Vis, DLS, XRD, FT-IR, and TEM analysis. The broth microdilution assay was applied to measure the Minimum Inhibitory Concentrations (MIC) of chemical AgNPs, biosynthesized AgNPs, and S. tebesana Bunge leaves extract alone against selected standard bacteria strains. The biosynthesized AgNPs displayed a surface plasmon resonance peak at approximately 415 nm, and the AgNPs synthesized using S. tebesana Bunge extract had a spherical configuration with an average size in the range of 10–15 nm. Biosynthesized nanoparticles showed a noteworthy antibacterial activity compared to chemical nanoparticles, particularly against P. aeruginosa, with the highest antibacterial activity reported at a MIC value of 39.06 μg/mL. AgNPs synthesized using S. tebesana Bunge extract demonstrated a significant decrease in fibroblast cell viability, but only when the concentration reached 2 mg/mL. The findings demonstrate that S. tebesana Bunge leaves extract enhances the antibacterial properties of AgNPs, and also represents an appropriate and biocompatible option for the synthesis of these nanoparticles. Our research highlights the potential of employing bio-safe and eco-friendly AgNPs synthesized in the presence of S. tebesana Bunge extract, which possess remarkable antibacterial properties, for various biomedical applications.

Silver nanoparticles enhance the mitigation of osmotic stress in Chenopodium quinoa microshoots grown under in vitro osmo-stressing conditions.

Osmotic stress is one of the main destructive abiotic factors that hinder plant growth and development. In this research, the role of silver nanoparticles (Ag NPs) in mitigating the negative impact of osmotic stress on in vitro grown Chenopodium quinoa (Quinoa 6 Line; Q6) was investigated to determine whether Ag NPs were able to reduce the negative effects on the in vitro grown cultures of the Q6 line. The explants were subcultured onto a special osmostressing media containing sucrose, sorbitol, or mannitol at different levels (0.1, 0.2, 0.3, and 0.4 mol/L) to mimic the osmotic stressing environment for four weeks. Then, stress physiological responses of in vitro grown Q6 under the induced osmotic stress were investigated to determine the highest stress level that the microshoots could tolerate. Next, Ag NPs; 25, 50, and 75 mg/L were added to the medium that contained the highest stress level of the induced osmotic stress to determine if their addition improved the physiological performance of the Q6 microshoots under the most severe osmotic agent levels. The results revealed that 0.4 mol/L sucrose, 0.3 mol/L sorbitol, and 0.3 mol/L mannitol were the highest stress levels that the microshoots could tolerate. The addition of 75 mg/L Ag NPs to the previous highest stress levels resulted in a significant increase in the following: stem length (SL), leaves number (LN), fresh weight (FW), dry weight (DW), total chlorophyll, protein, calcium (Ca), and phosphorus (P) contents, while it caused a reduction in proline, sodium (Na) ions, and potassium (K) ions. These results indicate that the negative consequences of osmotic stress on Q6 quinoa microshoots could be mitigated by adding specific concentrations of Ag NPs to the culture medium.

Anomalous spectral shift of localized surface plasmon resonance.

We report the first observation of spectral blue shift of plasmon resonance of synthesized silver nanoparticles (AgNPs) due to a negative optical nonlinearity of a local ambient medium, i.e., indigo carmine (IC) solution at around 420 nm wavelength. The blue shift occurred at a larger concentration of AgNPs or at a larger concentration of IC solution, being in obvious contrast to spectral red shift which was widely witnessed in plasmon spectral shift in a linear regime. Plasmon-enhanced local fields could excite the third-order optical nonlinearity for blue shift even under continuous (non-pulsed) light illumination. We also found that the plasmon-excited nonlinearity could allow for differential nonlinear response of the IC solution to be even greater than its differential linear response, though appearing to be somewhat inconsistent with what was generally known in light-matter interaction. The demonstrated properties of such anomalous shift of plasmon spectral peaks and its accompanying properties indicated that plasmon technologies could be exploited not only in linear but also in nonlinear aspects for critical optimization in plasmon-energy harvesting systems such as in surface enhanced spectroscopy/microscopy, biomedical imaging/sensing, laser frequency conversion, ultrashort pulse generation, and all-optical switching.

Antimicrobial Activity of Hydrophilic Sealants incorporated with Green Synthesized Silver nanoparticles-An invitro Study

Background: Dental caries formation is highly prevented by applying pit and fissure sealant but was associated with microleakage and secondary caries formation. Aim and Objectives: To synthesize novel pit and fissure sealant with green synthesized silver nanoparticles and evaluation of antibacterial activity against Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Candida albicans. Materials and Methods: Green synthesis of silver nanoparticles was done using beetroot, characterized using FTIR (Fourier transform infrared), EDAX (Energy Dispersive X-ray Analysis), and Scanned Electron Microscope Analysis. A novel pit and fissure sealant was made by incorporating synthesized Ag nanoparticles and hydrophilic nature from Ultra seal XT Hydro. Using amoxicillin as a control, an agar well diffusion method was used to conduct an antimicrobial test for a new sealant against Staphylococcus aureus, Streptococcus mutants, Enterococcus faecalis, and Candida albicans in Muller Hinton Agar for each organism. Result: Zone of inhibition was measured, showing statistically significant antimicrobial activity against Streptococcus mutans with the ZOI value at concentration of Ag nanoparticles in sealant material. Conclusion: Novel Hydrophilic pit and fissure sealant with Ag nanoparticles are potentially antibacterial against the cariogenic microorganism. Thus, it can be utilized for the better efficiency of topical pit and fissure sealant preventive therapy.